Effect of Fe Doping Profile on Current Collapse in GaN-based RF HEMTs

Area of Science:

• Materials Science
• Semiconductor Device Physics
• Electrical Engineering

Background:

• Current collapse in Gallium Nitride (GaN)-based high electron mobility transistors (HEMTs) is a significant challenge for device performance.
• Iron (Fe) doping is employed in GaN HEMTs, but its impact on current collapse requires detailed understanding.
• Understanding the Fe doping profile's influence is crucial for fabricating reliable GaN RF HEMTs.

Purpose of the Study:

• To systematically investigate the impact of Fe doping profiles (concentration, decay rate, depth) on current collapse magnitude (▵CC) in 0.5-μm gated GaN HEMTs.
• To elucidate the physical mechanisms responsible for current collapse related to Fe doping.
• To identify optimal Fe doping strategies for reducing current collapse in GaN-based RF HEMTs.

Main Methods:

• Utilized Technology Computer-Aided Design (TCAD) simulations to model and analyze Fe doping effects.
• Developed accurate simulation models to guide experimental fabrication.
• Investigated the interplay between trapping/de-trapping of Fe-related traps and current collapse.

Main Results:

• Fe doping concentration and decay rate significantly influence current collapse more than doping depth.
• Increased trap state density near the two-dimensional electron gas (2DEG) channel exacerbates current collapse.
• A reduction in ▵CC by approximately 50.3% was achieved by optimizing the Fe doping profile.

Conclusions:

• The current collapse in GaN HEMTs is attributed to the trapping and de-trapping dynamics of Fe-related defects.
• Optimized Fe doping profiles, considering concentration, decay rate, and depth, are essential for mitigating current collapse.
• This research provides a pathway for fabricating GaN-based RF HEMTs with significantly improved performance by limiting current collapse.